The field of the invention is that of systems of radiocommunications with mobiles.
The invention can be applied especially but not exclusively to radiocommunications systems such as the UMTS (Universal Mobile Telecommunication System), GSM 900 (Global System for Mobilesxe2x80x94900 MHz), DCS 1800 (Digital Cellular Systemxe2x80x941800 MHz) or PCS 1900 (Personal Communication Systemxe2x80x941900 MHz) type systems.
More specifically, the present invention relates to a method for the testing of a radiocommunications network that consists in detecting and elucidating the nature of the interference between at least two transmitters, namely one the one hand a mobile station emitting useful signals towards a base station and, on the other hand, at least one interference unit sending interference signals also towards the base station.
It may be recalled that a radiocommunications system generally comprises a plurality of base stations, each carrying out the radio coverage of a distinct geographical cell.
Hereinafter in the present description, the term  less than  less than interference unit greater than  greater than  (with respect to a given mobile station) is understood to mean any type of device that is sending a base station, with which a given mobile station is communicating., signals having at least certain characteristics that are identical or similar to those of the signals coming from the given mobile station.
Depending on the system, the mobile station is sometimes called a radiocommunications terminal, a portable radiotelephone, a portable telephone or again a mobile radiocommunications terminal. With a view to simplification, only one expression,  less than  less than mobile station greater than  greater than  will be used hereinafter in this patent document.
It will be recalled that a mobile station is a piece of physical equipment used by a user of a network of the radiocommunications system to obtain access, through a base station, to the telecommunications services on offer.
It will also be recalled that a base station covers a given geographical zone (or cell) in which a plurality of mobile stations, with which the base station can exchange signals, may move about. Conventionally, a base station comprises at least one antenna designed to receive and/or transmit signals from and/or to a plurality of mobile stations.
The signals exchanged between a mobile station and the base station may be subject to interference that could generate a partial or even total loss of the information conveyed. It may be recalled that interference phenomena are caused especially when signals having identical or similar characteristics are brought into play in the same propagation medium. The expression  less than  less than identical or similar greater than  greater than  characteristics is understood to mean one and the same frequency, one and the same code or one and the same time interval depending on whether the type of multiplexing used is the Frequency Division Multiple Access (FDMA), Coded Division Multiple Access (CDMA) or Time Division Multiple Access (TDMA) type of multiplexing. In other words, the interference phenomena are due to the presence of at least one interference unit sending signals (called  less than  less than interference greater than  greater than  signals) which disturb the signals (called  less than  less than useful greater than  greater than  signals) sent by a mobile station. It will be understood therefore that such disturbances may generate crucial problems in terms of quality of reception and exploitation of the signals sent by a mobile station and intended for a base station.
Now, it is not possible, in the prior art, to detect the presence of an interference unit or units. It will be understood, however, that in order to reduce or even eliminate the interference due to one or more interference units, it is necessary to know about their existence and, if necessary, their nature, in order to take appropriate measures in order to try and eliminate them.
The present invention is designed especially to overcome this drawback of the prior art.
More specifically, one of the goals of the present invention is to provide a method for the testing of a radiocommunications network enabling the detection of the presence of at least one interference unit.
It is an additional goal of the invention to provide a method of this kind making it possible to determine the possible nature of the interference unit or units.
Another goal of the invention is to provide a method of this kind that can be implemented without any modification of the signals exchanged between a mobile station and a base station.
Another goal of the invention is to provide a method of this kind that can be implemented without any hardware modification of the existing mobile stations or, as the case may be, of the base stations.
Another goal of the invention is to provide a device enabling the implementing of a method such as this for the testing of a radiocommunications network.
These different goals as well as others that shall appear hereinafter are achieved according to the invention by means of a method for the testing of a radiocommunications network consisting in detecting and elucidating the nature of the interference between at least two transmitters, namely on the one hand a mobile station sending useful signals towards a base station and, on the other hand, at least one interference unit sending interference signals also towards said base station, the method comprising the following steps:
downline from a first antenna, a first reception line is implemented and, downline from at least one second antenna, at least one second reception line is implemented distinct from said first reception line, each antenna comprising an array of radiating elements distributed in a matrix arrangement on a support;
said first reception line is assigned to the reception of first signals, in a first incoming direction;
said at least one second reception line is assigned to the reception of second signals, in at least one second incoming direction;
each reception line tries to decode the signals that it receives and, if the decoding can be done, it reads an identifier that is conveyed by the signals and is proper to the transmitter that has sent them, so as to determine firstly which of said first and second signals are said interference signals and, secondly, at least one of the pieces of information belonging to the group comprising:
the incoming direction of said interference signals
the identifier, if any, of said at least one interference unit sending said interference signals.
The general principle of the invention relies therefore on the simultaneous focusing of several RF reception radiating beams (one per antenna) respectively on different sources of signals (namely, a source of useful signals and one or more sources, if any, of interference signals. Thus, at least one reception line is allocated to the processing of possible interference signals.
In this way, it is possible not only to know if one or more interference units are present but also to locate their angular position and find out their nature as the case may be.
It must be noted that the terms  less than  less than first antenna greater than  greater than  and  less than  less than second antenna greater than  greater than  (known as a  less than  less than smart antenna greater than  greater than ) have been used to simplify the understanding of the invention. It is clear, however, that it is not obligatory that there should be as many antennas as there are reception lines. In other words, the first and second antennas may constitute a single antenna.
It is also possible to plan that at least certain radiating elements of one and the same support should be shared by several antennas.
Advantageously, said incoming direction is expressed as a function of at least one of the angles belonging to the group comprising:
the azimuth;
the elevation angle.
It is recalled that an antenna associated with a reception line forms an RF reception radiating beam that may be oriented in elevation angle (namely the angle formed between the line connecting the mobile station to the antenna and the horizontal plane containing the support of the antenna) and/or the azimuth, (namely the angle formed between the line referenced in the horizontal plane containing the support of the antenna and the projection, in a direction perpendicular to this horizontal plane, of the line connecting the antenna to the mobile station).
Preferably, said at least one interference unit belongs to the group comprising:
the mobile stations of said radiocommunications network
the base stations of said radiocommunications network
the transmitters not belonging to said radiocommunications network
It will be noted that the nature of the interference unit or units may be unspecified, and may especially correspond to that of one or more interference units that are unrelated to any radiocommunications network.
In a particular embodiment of the invention, said method furthermore comprises a step for the display of at least one of the pieces of information belonging to the group comprising:
the identifier or absence of identifier of said at least one interference unit;
the incoming direction of the interference signals.
It will be noted that when an interference unit proves to be a mobile station or a base station of the radiocommunications network, the method of the invention constitutes a technique for detecting the imperfections of the radiocommunications network concerned. Indeed, this reflects a poor management of the distribution of the resources such as a double allocation of one and the same resource. This is the case, for example, when there are two neighboring (or relatively close) base stations both using at least one communications parameter that is the same, for example a frequency, a code, a time interval, etc., each to communicate with a separate mobile station.
Preferably, said base station and said mobile station are included in a cellular radiocommunications system belonging to the group comprising:
UMTS type systems
GSM 900 type systems
DCS 1800 type systems
PCS 1900 type systems
It is clear however, that this list is not exhaustive.
The invention also relates to a device for the testing of a radiocommunications network designed to implement the method described here above. According to the invention, said device comprises:
a first antenna and a second antenna each comprising an array of radiating elements distributed in a matrix arrangement on a support;
downline from said first antenna, a first reception line comprising first reception means and, downline from said at least one second antenna, at least one second reception line distinct from said first reception line and comprising second reception means;
means for assigning said first reception line to the reception of first signals, in a first incoming direction;
means for assigning said at least one second reception line to the reception of second signals, in at least one second incoming direction;
means for decoding the signals received by each of said reception lines;
reading means placed downline from said decoding means so as to read an identifier conveyed by the signals and proper to the transmitter that has sent them;
decision-making means making it possible, as a function of output signals from said decoding and reading means, to determine firstly which of said first and second signals are said interference signals and, secondly, at least one of the pieces of information belonging to the group comprising:
the incoming direction of said interference signals
the identifier, if any, of said at least one interference unit sending said interference signals.
It will be recalled however that, according to one alternative embodiment of the invention, it is possible to provide for a single antenna supplying the different reception lines of the signals (useful signals and one or more sources of interference signals). In this case, it will be understood that the first and second antennas constitute one and only one antenna.
The invention also relates to a base station that makes it possible to detect and elucidate the nature of the interference phenomena between at least two transmitters, namely, on the one hand, a mobile station sending useful signals to said base station and, on the other hand, at least one interference unit sending interference signals also to said base station. According to the invention, said base station comprises the above-described device for testing a radiocommunications network.
It will be noted that certain elements (such as the first antenna and the first reception line) of the testing device are elements already included in the base station to enable it to communicate with the mobile stations. In this case, there is a high degree of synergy and the cost of the testing device is thus limited solely to the elements not already included in the base station.